anaerobic bacteriology

anaerobe

org grows readily under anaerobic conditions (5-10% CO2, 5-10% H2, 80-90% N2) but minimally/not under aerobic (5-10% CO2 in air) on nutritionally adequate medium

superoxide dismutase, catalase

-protective enzymes in presence of O2

-lacked by anaerobes

obligate aerobes

-20% O2

-Mycobacteria

-fungus

microaerophile

-2-8% O2

-Campy

facultative anaerobe

-grow well with or without O2

-Staphs

-Streps

-Enterobacteriaceae

aerotolerant

-reduced O2

-anaerobic and microaerophilic

-Clostridium tertium

-Cutibacterium acnes

-Lactobacillus

obligate anaerobes

-strict anaerobes

-0% O2

-Bacteroides

-Clostridium

capnophiles

-req 5-10% CO2

-Neisseria

-Haemophilus

no

yes/no: acceptable specimens for anaerobic bacteria

-swabs (throat, abscess, vaginal, gingival, skin), sputum, tracheal aspirates, BALs, catheterized urine, clean catch urine

syringe

best collection method for anaerobic specimens 

-abscesses

prereduced gel

least optimal method of collection of anaerobic specimen

E-swab, Aimes

anaerobic specimen transport tubes

Brucella blood agar (BRUC/BA)

most common nonselective agar for anaerobic media

anaerobic blood agar (CDC)

-SBA with vit K and hemin (X)

-nonselective agar for best recovery

thioglycollate broth

-nonselective anaerobic media

-chopped meat with glucose

-cooked meat

laked blood kanamycin vancomycin agar (LKV/KVLB)

-selective agar

-anaerobic GNB

-Bacteroides

-Prevotella (pigmentation)

anaerobic GNB (Bacteroides, Prevotella)

what LKV is selective for

kanamycin, vancomycin

antibiotics in LKV agar

Bacteroides bile esculin (BBE)

-selective agar

-bile-tolerant anaerobes

-clear yellow

-black: pos

-gram neg grow in 20% bile

-Bacteroides fragilis

Bacteroides fragilis

what BBE agar is selective for

phenylethyl alcohol, colistin nalidixic acid (PEA, CNA)

-selective agar

-gram pos anaerobes

-inhibits facultative anaerobes (Enterobacteriaceae)

gram pos anaerobes (GPA)

what PEA and CNA agars are selective for

egg yolk agar (EYA)

-selective agar

-lecithinase: halo = pos

-lipase: metallic sheen = pos

cycloserine-cefoxitin fructose agar (CCFA)

-selective agar

-C. difficile

C. difficile

what CCFA agar is selective for

aerobes

-grow on BA aerobically in non CO2

-grow on CHOC aerobically in CO2

-do not grow on BA anaerobically

capnophile

-do not grow on BA aerobically in non CO2

-grow on CHOC aerobically with CO2

-do not grow on BA anaerobically

facultative anaerobe

-grows on BA aerobically in non CO2

-grows on CHOC aerobically in CO2

-grows on BA anaerobically

obligate anaerobe

-does not grow on BA aerobically in non CO2

-does not grow on CHOC aerobically in CO2

-grows on BA anaerobically

gram stain, aerotolerance, antibiotics

presumtive ID for anaerobes

sodium polyethanol sulfonate (SPS)

antibiotic disk for gram pos cocci ID

vancomycin, kanamycin, colistin

antibiotic disks for anaerobic gram neg rod ID

MALDI TOF

definitive ID of anaerobes is done by …

Bacteroides fragilis

-vanc: R

-kan: R

-col: R

pos, spore

Clostridia spp anaerobic gram pos/neg, spore/non

Clostridium perfringens

-food poisoning pathogen

-types A (mild, spore) and C (fatal, toxin)

-large, box car shaped, gram pos rods

-double zone beta hemolysis on SBA/BAP

-lecithinase: pos

type A food poisoning

-mild Clostridium perfringens inf

-self lim GI illness

-enterotoxin linked to spore

type C food poisoning

-fatal Clostridium perfringens inf

-fatal

-beta toxin

-severe bloody diarrhea

-SI necrotic inflamm

botulism

caused by Clostridium botulinum

Clostridium botulinum

-lecithinase: neg

-lipase: pos

-botulism

-toxin mediated (A-G, humans A,B,E)

-A modif for botox, wandering eye treatment

-neurotoxin: SI and nervous system

-home-canning

-infants: honey

-bioterrorist: potent

tetanus

caused by Clostridium tetani

Clostridium tetani

-lecithinase: neg

-lipase: neg

-indole: neg

-terminal spores

-swarming

-spore entry through wound

-tetanospasmin

tetanospasmin

Clostridium tetani neurotoxin

-affects inhibitory neurons → prevent neurotransmitter release

Clostridioides difficile

-non-reactive (neg)

-toxin A: diarrhea

-toxin B: pseudomembranous colitis

-culture on CCFA

-chartreuse fluorescence

-horse stable odor

-GLDH: pos (toxin)

cycloserine cefoxitin egg yolk fructose agar (CCFA)

C. difficile culture agar

-pink → yellow with C. diff

C. difficile

CCFA: colonies yellow “ground glass” 

-agar pink → yellow

glutamate dehydrogenase (GLDH)

rapid screen for C. diff

-test for toxin

Clostridium septicum

-non-reactive (neg)

-spreading/swarming: “medusa head”

-subterminal spores

-bacteremia assoc w blood or bowel malignancies

Cutibacterium acnes

-tiny GPB, pleio, diphtheroid

-indole: pos

-catalase: pos

-blood culture/tissue contaminant (false pos)

-skin flora

-occasional pathogen: joint replacement inf, bacteremia, subacute bact endocarditis

Actinomyces

-catalase: neg

-indole: neg

-slow growing (10 days), fastidious

-branching, filamentous GPB

-cervicofacial actinomycosis (dental, face/jaw)

-thoracic actinomycosis (aspiration)

-IUD inf

Actinomyces israelii

molar tooth colonies

Lactobacillus

-catalase: neg

-vanc: R

-aerotolerant aerobe

-mouth, GI, FGT flora (urine, genital cultures)

-colonies: pinpoint, alpha hemolytic

-pleio GPB, long thin rods

Bifidobacterium

-catalase, indole: neg

-pleio GPR, “dog biscuit” ends

-mouth and GI flora

Eubacterium

-catalase, indole: neg

-pleio GPB

-mouth, colon inf

Peptostreptococcus, Finegoldia, Peptoniphilus

GPC in chains

-mouth, GI, vagina, skin flora

-polymicrobial inf

-gingivitis, peridontal diseases, lung absc, pneumonia

Peptoniphilus asacchrolyticus

-SPS: R

-indole: pos

Peptostreptococcus anaerobius

-SPS: S

-indole: neg

Bacteroides fragilis

-GNB

-most often encountered

-mouth, GI flora

-peritoneal inf

Bacteroides fragilis

-BBE: bile escullin: pos

-indole: neg

-catalase: pos

-vanc, kana, col: R

-beta lactamase: pos

Prevotella, Porphyromonas

-upper respiratory flora

-GN coccobacilli

-brick red fluorescence

-porphyrin producers: brown/black colony pigment

Porphyromonas

-GN coccobacilli

-indole: pos

-vanc: S

-kana: R

-col: R

-LKV, BBE: no growth

-brick red fluorescence

Prevotella

-GN coccobacilli

-indole: var

-vanc: R

-kana: R

-col: var

-LKV: growth

-BBE: no growth

-brick red fluorescence

Fusobacteria

-GNB

-oral flora

-chartreuse fluorescence

-vanc: R

-kana: S

-col: S

-SBA: large, white

-indole: pos

Fusobacteria nucleatum

-lipase: neg

-LKV: no growth

-long, fusiform GNB

-breadcrumb/ground glass colonies

-mouth inf

Fusobacterium necrophorum

-lipase: pos

-LKV: growth

-pleio GN coccobacilli

-tonsil inf: Lemierre syndrome

-acute gingivitis: Vingent angina

Veillonella

-GNC

-oral, vaginal, upper respiratory, GI flora

-vanc: R

-kana: S

-col: S

-catalase: pos

-indole: neg

-weak red fluorescence

metronidazole, beta lactam combo

broad spectrum antibiotic treatment for non sterile sites with GNA recovery

beta lactamase

test for penicillin susceptibility

sterile

CLISI suggests susceptibility testing for sterile/nonsterile sites